I have an '82 XT550. It hadn't run in 7 years. I carefully cleaned up the carb and reinstalled (twice, actually - wasn't sure I got it clean the first time). The coil checked out bad, so I replaced it with an Emgo universal (one wire, vs. stock 2 wire, but stock coil has the black wire grounded, which is what I did with the replacement).

I had trouble starting it at first, but this morning it fired up fine, with choke on. Idled normally, and revved up OK. After I figured it was warm enough, I pulled back the choke and it died. No big deal, except now it won't restart.

Fuel issue, either carb or tank. Did you drain the tank and put in fresh fuel? Is there an inline fuel filter between the tank and carb? Rust in the tank? Filters on the petcock clogged?

Between a 30 year old fuel tank and sitting for 7 years, I'd start with the fuel tank first. Drain, flush, and inspect. Rust in the tank? If there is, that will have to be addressed. Check the filters on the petcock. Then disconnect the fuel line going into the carb and turn on the petcock to make sure you have good fuel flow to the carb. If that all checks out, then the problem is in the carb itself. The jets in a carb are tiny and it doesn't take much to clog them. The fact that it runs with choke but not without is a good sign of a clogged jet. Also could be your float is stuck and not allowing more fuel into the carb. Try the float bowl drain and see if fuel comes out.

Lots of things to check and any one of them will stop it dead. The good part is most are really easy fixes you can do yourself and pretty cheap parts.

A little more info (I am home because the chimney guy is here, but in work clothes so I can't tear into it now).

If I kick it over a few times, throttle open, key off, then kick it with the key on, throttle closed it sounds like it wants to pop (this is what it was doing before it wouldn't start). So, sounds like it needs a little more fuel floating around?

The idle screw was set about 2 turns out when I took it apart. I reset it to 1.5 per spec that I read somewhere (the cap had been removed already). I didn't assume that it was right because it was a CA bike (I am at 7,400 feet), but maybe I should turn it out a little more?

Most common problem is the smallest passages don't get cleaned, most newbs blissfully unaware they exist, where to look for them, cross drillings, etc. Not magic, simple physics (vacuum) and a bit of hardware.
Whenever cleaning a carb, you MUST verify flow in all passages... again for the back row, you MUST VERIFY FLOW in ALL PASSAGES! Use aerosol spray brake cleaner, and make sure it comes out AS EXPECTED!

And, uh, set the idle so it would run when started with throttle off (too paranoid of kickbacks to hold it open when starting) and won't stall when choke is shut off. Started, ran around the 'hood, shut off and restarted. So far so good.

I was pretty sure I got all the little passages the first time, but that's why I took it apart again and used carb cleaner and compressed air.

Anyway, I am getting better at getting the carbs in and out,

and thanks for the tips.

EDIT: Yep, just needed the idle turned up (certainly, it did need all the cleanup as well), so I am good to go. Whooo hoo!